Method of treating strands



Aug. 31, 1943. F. R. REEVEILY METHOD OF TREATING STRANDS original Filed May' 211938 ekm'wpem A 7' TORNE Y Vor another specific purpose.

stances a solvent or vehicle is used which is yola-4 Patented Aug. 31,1943

ivm'rnon or Tammo s'rimms Frederick R. Reevcly, St. Lambert, Quebec, Canada, assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Original application May l 21, 1938, Serial No.

209,395. Divided and this application November 18, 1939, Serial No.305,079

8 Claims.l

This invention relates to a method of treating strands, and more particularly to a method of coating strands, especially electrical conductors, with viscous liquid or plastically pasty materials.

insulating sheathings on electrical conductors are made, at the present time, ina multitude of companying drawings in which the same reference numerals are applied to identical parts in ways, somevof which include the application to a bare or previously variously sheathed strand of hardenable materials applied in liquid, semiliquid, or pasty form and subsequently hardened. Thus materials in the nature of paint, enamel, varnish, or waxes, asphalts, paraflins and the like dissolved in volatile vehicles, articial resins hardenable by polymerization induced by heat, and other analogous materials are used for one In many such intilized to be subsequently recovered, and a considerable part of the cost of the coating operation may arise out of the volume of material to be recovered for subsequent re-use. Hence it is desirable and may be vitally important to apply the raw sheathing or sheath treating material in a condition approaching dryness as nearly as may Ibe practicable, i. e. as a liquid of high viscosity or even a smoothly plastic paste, in order that the volume of vehicleor solvent circulated in the process, or perhaps wasted, may be kept low.

An object of the present-invention is to provide an improved method for forming a. coating of material, such as described above, upon a strand, in which the material mayV be of a viscous or stiilly liquid nature or even a plastic paste, and in which the material may be applied thickly and yetluniformly.

With the above and other objects in'view, thev invention in one form may be embodied in a method of applying on astrand a coating of predetermined thickness of a coating material in a highly viscous plastic form, which process comprises steps of passing a strand to be coated through a body 'of the coating material whichis under pressure to thereby form an excessive coating of the material on the strand, and wiping the excessively coated strand witl'ra wiping pressure proportionate to the pressurel on the body of coating material.

Other. objects and features of the invention will appear from the following detailed, description ci one embodiment thereof in an apparatus for practicing the method of the invention to apply a' viscous mixture ofcelluloseacetate in ail acetone vehicle to a textile covered electrical conductor strand, taken in connection with the'ac- 'ing plug shown in Fig. 2; and

'mentat an elevated temperature.

the several gures, and in which AFig. 1 is a view in side elevation of the apparatus with a portion of one wall broken away;

Fig. 2 is a broken enlarged view in horizontal section of one of the twin applicator heads of the apparatus;

Fig. 3 is a detached, further enlarged view in longitudinal central section of the die support- Fig. 4 is a. corresponding View thereof in end elevation.

The apparatusv herein disclosed comprises,

roughly, means to apply a viscous or pasty ma- .terial to a strand combined with means to harden i the applied material on the strand, the two being so constructed and arranged that the process of Y hardening begins immediately the coating is applied with a `step of preliminarily hardening at room temperature and subsequent further treat- This apparatus and the process to be carried out by it generally form no part of the present invention, being fully disclosed and claimed in copending application Serial No. 209,396, led May 2l, 1938, by the present inventor and two others. The apparatus generally is disclosed herein only Ain so far as is necessary for a clear understanding of the present invention and reference may be had to the copending application mentioned if necessary for the construction and functioning of the apparatus generally. The specic. structure of the die and its mounting, however, is the subject of copending application, Serial No. 209,395, led May 21, 1938, by the present inventor, and upon which application U. S. Patent 2,218,482 was issued 0n October 15, 1940;- and of which application the present one is a division.

The` heart of the paste applyingq means is a twin applicator device best shown in Fig. 2, and generally indicated by the numeral 20. Since this is a twin, a description of one side only will suiiice for both. An individual applicator' comprises a cylindrical b ody member 2|` having a chamber 22 therein, through which passes a' strand 4|9.to be coated. The strand enters the chamber through an axially bored plug 24 mounted in the rear wall of the chamber, the bore 25 of the plug being suflici'ently large to pass the strand without ,harmful friction. The forward end of the plug extends taperlngly into the chamber as at 26. Another plug 21 is mounted in the front wall of the chamber and has housed completely therein a wiper Adie member 28. This member or die 28 is abody of soft vulcanized rubber or similar material and is given any convenient shape. The particular member or die.28 illustrated is an ordinary soft rubber bottle/stopper of suitable size. The plug 21 is recessed to ilt the member 28 which is held in place inithe plug by any suitable means such as the removableretainer 3U.

The'plug 2 and retainer 30 are axially bored to pass the strand I9 with liberal clearance for both the strand and its raw coating. The die member 28 is formed with an axial bore of such size as to pass the strand I9 bearing a raw coating of predetermined desired thickness, and the member 28 acts tovwipe oi any superuous thickness of coating. i

The twinapplicators 2@ may conveniently be supported, as shown, upon the upper end of a vertical feed pipe 3l which serves to bring coating material under pressure to the chambers 22 as well asto'support the twin applicators. A valve 32 mounted in the feed pipe serves to control the flow of coating material from a supply tank 33 through the pipe to the applicators. A supply of air or of some inert gas, nitrogen, carbon dioxide or other similar gas according the nature of the coating material under pressure is fed into the upper part of the tank 33, preferably above the level of the coating material therein, through a pipe 34 from a suitable supply 35 of the compressed gas. If desired an indicating pressure the invention as pointed out in and limited solely by the appended claims.

What is claimed is:

L A. process of applying on an electrical conductor strand a coating of predetermined thickness of a coating material in a highly viscous plastic form, which process comprises steps ofl passing 'a strand t be coated through a body of the coating, material. exerting pressure upon the body of coating material to thereby `form an excessive coating of the material on the strand, and wiping the excessively coated strand with a wiping pressure generated by the pressure on the body of coating material to be variable with variations of the pressure on the material.

3. A process of applying on a strand a coating u ,of predetermined thickness of a coating material gage 36 may be mounted`at any convenient place and connected by a pipe 31 to the pip'efl. f

A characteristic feature of the invention is that `the die supporting plug 2 has the walls of its die receiving recess formed with longitudinal ilutings or grooves 29, so that the' member 2l touches the lateral outer wall of the die member 28A only along the narrow edges of the ribs between the grooves 29. Thus these grooves 29, when the assembly is complete as in Fig. 2, provide chambers or recesses covering most of the outer lateral surface of the die 28, open at. their rear ends to Y the coating material chamber 22,v and closed at `theirfront ends by the member 30.

In this manner, the pasty material under presi sure in the chamber 22 iiows into these' grooves 29 and thus surrounds and is in contact with substantially the entire outer lateral surface of the compressible die 28.v As a result, Aif for any reason the pressure in the chamber 22 becomes excessive' and tends to form toc thick a coating on the strand by forcing too much material to accompany the strand through the die, the die Will bev compressed correspondingly, andl so correspondingly increase the severity of the Awiping eiect of the dieby decreasing `the diameter of its bore. The strand i9 thus provided with raw coating material then passes from the applicator through the adjacent hardening and curing devices and `may then be considered to be nished, or may be returned through the other side ofthe twin in a highly viscous plastic form, which process comprises steps of passing a strand to be coated through a body of th coating material, exerting pressure upon the body of coating material to thereby form an excessive coating of the material on the strand, and wiping the excessively coated strand with a wiping pressure varying in accordance With variations of the pressure on the body of coating material.

4:. A process of applying on a strand a coating of predetermined thickness of a coating material in a, highly viscous plastic form, which process comprises steps of passing a strand to becoated through a body of the coating material, exerting pressure upon the body of coating materialY to thereby form an excessive coating of the material on the strand, and wiping the excessively coated strand with a wiping pressure generated by the pressure on the body of coating material to be variable with variations of the pressure on the -materiaL 5. A process of applying on a strand a coating of predetermined thickness of a coating material applicator to` receive a`secondraw coating and V thence through the hardening and curing again.

' As noted beforeI the present invention relates only Jto the method of application. `vAs herein disclosed the invention is illustrated by means of apparatus `for applying pasty -coating material to -a strand. Itmight obviously, however, be also used for liquid materials if desired, so only that the material in question be supplied under pressure to the chamber 2,2- or equivalent thereof. The particular embodiment disclosed'isillustrative and may be'modied and departed from 'without departing from the spirit and scope of vin a highly viscousplastic form. which process comprisessteps of passing a strand to be coated through a body of the coating material, exerting pressure upon the bodyA of coating material to thereby'form an excessive coating of the mate-V rial on the strand, and wiping the excessively coated strand with a wiping pressure circumferentially uniform and varying in accordance with variations of the pressure on the body of coating material.

` 6. A process of applying on a strand a coating of predetermined thickness of a coating material in a. highly viscous plastic form, which process comprises steps of passing a strand to be coated through a, body ofthe coating material, exerting pressure upon the body of coating material to therebyv form an excessive coating of the material on the strand, and wiping the excessively'coated' strand with a wiping pressure circum'ferentiallyl uniform and generated by the pressure on the vbody of coating material to be variable with w variations of the pressure on the material.

v 7. A process of applying on a strand a coating of predetermined thickness of a 'coating material in a 'highly viscous .plastic ,iorm,. Which process comprises steps of passing a strand to be coated in a highly viscous plastic form, which process comprises' steps of passing a strand to be coated l through a body of the coating material, exerting through a body of the coating material, exerting pressure upon the body of /eoating material to thereby form an excessive coating of the material onl the strand, wiping the excessively coated strand with a compressible member surrounding the strand, and simultaneously subjecting the member'to compression. varying in intensity inl accordance withvariations in the pressure on the coating material to thereby maintain a wiping pressure on the coated strand varying in ac-v cordance with/'variations in the pressure on the coating material.

8. A process o1' applying on a strand a-coating of predetermined thickness of a coating material tensity in accordance'with variations in the pressure on the coating material to thereby maintain a wiping pressure on the coated strand varying in accordance with variations in the pressure o n the coating material.

FREDERICK R. REEVE'LY. v 

